Researchers Compare Diffusion of Xenon and Nitrous Oxide into the Bowels of Pigs during Anesthesia.

Researchers Compare Diffusion of Xenon and Nitrous Oxide into the Bowels of Pigs during Anesthesia.Reinelt et al. (page 475)

A well-known side effect of nitrous oxide anesthesia is its diffusion into air-filled spaces, such as the bowel. Parameters that define the amount of gas diffusion are well-known for nitrous oxide but not for xenon, an inert gas with a blood–gas partition coefficient of 0.12¹–0.14². Accordingly, Reinelt et al.  randomly assigned 21 pentobarbital-anesthetized pigs to administration of xenon–oxygen, nitrous oxide–oxygen, or nitrogen–oxygen, all in mixtures of 75/25. After median laparotomies, four segments of small intestine, 15 cm long in each animal, were isolated and occluded with elastic rubber bands. Pressure in each of the bowel segments was monitored for 1 h before the start of the experiments to exclude possible gas losses. During the 4-h anesthesia periods, arterial blood pressure and pressure in the bowel were measured continuously and were recorded every 30 min. Pressure and volume values of the four bowel segments were averaged for each animal at corresponding measuring points.

There were no detectable gas leaks before or after the test period. Nitrous oxide and xenon both led to an increase of the intraluminal gas volumes compared with the nitrogen–oxygen control group, although the volumes were greatest in the nitrous oxide group. The median volume of bowel gas in animals to which inhalational nitrous oxide was administered was 88.0 ml, compared with 39.0 ml for xenon anesthesia and 21.5 ml in the nitrogen–oxygen group. Xenon has a relatively low blood solubility, an important factor influencing its diffusion into air-filled cavities.